15- Create a question regarding the Kinetic energy and solve it? 16- Create a question regarding the Potential energy and solve it?

### 15. Kinetic Energy Problem **Question:** A car with a mass of \(1200\,\text{kg}\) is moving at a speed of \(20\,\text{m/s}\). Calculate its kinetic energy. **Solution:** 1. The formula for kinetic energy is \[ KE = \frac{1}{2}mv^2 \] 2. Substitute the given values into the formula: \[ KE = \frac{1}{2} \times 1200 \times (20)^2 \] 3. Calculate the square of the speed: \[ (20)^2 = 400 \] 4. Multiply the values: \[ KE = \frac{1}{2} \times 1200 \times 400 \] First calculate \(\frac{1}{2} \times 1200 = 600\), then \[ KE = 600 \times 400 = 240000\,\text{Joules} \] --- ### 16. Potential Energy Problem **Question:** A rock of mass \(3\,\text{kg}\) is lifted to a height of \(15\,\text{m}\) above the ground. Calculate its gravitational potential energy. Assume the acceleration due to gravity is \(9.8\,\text{m/s}^2\). **Solution:** 1. The formula for gravitational potential energy is \[ U = mgh \] 2. Substitute the known values: \[ U = 3 \times 9.8 \times 15 \] 3. First, calculate the product of the mass and gravitational acceleration: \[ 3 \times 9.8 = 29.4 \] 4. Then, multiply by the height: \[ U = 29.4 \times 15 = 441\,\text{Joules} \]